Patients with acute myocardial infarction (AMI) are in critical condition. When primary percutaneous coronary intervention (PCI) was performing, no-reflow, reperfusion injury，heart failure, heart rupture, malignant arrhythmia maybe happen. It was reported remote ischemic preconditioning (RIPC) may play an effective endogenous cardiac protection. This study will investigate whether once RIPC before primary PCI or long-term RIPC can improve AMI patients short-term and long-term (1 year) prognosis. 400 STEMI patients undergoing primary PCI were randomly divided into 3 groups: long-term RIPC group (once preoperative RIPC and once RIPC/day after PCI), preoperative RIPC group (once preoperative RIPC), control group (without RIPC). Cardiac troponin (TNI), high-sensitivity C-reactive protein (hsCRP), adenosine, vascular endothelial growth factor (VEGF), hypoxia inducible factor-1 (HIF-1), echocardiography and magnetic resonance （MR）were detected 1 day, 1 month and 1 year after PCI. Patients will be followed up by telephone at the end of one year. The major adverse cardiovascular events (MACE) include cardiovascular death, spontaneous myocardial infarction, unplanned revascularization and stroke.